<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        'use strict';
        //遍历数组
        var arr = [2, 3, 4];
        for (let x of arr) {
            alert(x);
        }

        //遍历map
        var map = new Map(['tom', 10], ['jack', 20]);
        for (let x of map) {
            alert(x);
        }

        //遍历set
        var set = new Set([5, 6, 7]);
        for (let x of set) {
            alert(x);
        }
    </script>
</head>
<body>

</body>
</html>